Mystery electrical problem,help

[The Mighty Gryphon]

"No load" voltage on a good fully charged battery should be around 12.8 volts. 

What matters is what a load test shows.  You can have that done at the local auto parts shop.

What is the charging rate of your charger?  The brick battery is fully charged with 19-21 amp hours.  If you are trying to charge a dead battery with a 50ma "trickle charger it will take approximately 240 hours to get a usable charge if it will charge the battery at all.

[Kchop]

Hey guys,
So installed a new voltage regulator. Same result.
No load on battery 12.41
Max Voltage at 2000 rpm 13.35

To answer Gryphon: Tried 1a charger as well as 5A charger. So, even though 1a charger was on roughly 16 hours, and registered full charge (Green), are you saying this might not be enough for full charge on battery?? Also, wouldn't battery charge to full if driving a couple of hours??

Ingo: when are registering 14.4 V . When bike on and running??
Thanks

[daveson]

Maybe there's nothing wrong with the alternator, the reason it stopped when you removed the battery terminal is because the key was in the off position.

The battery still isn't fully charged and it's not very old. If your bike sits around for long periods without being used, it might help to charge it with a smart charger.

There might be an unwanted drain on your battery. You say the bike stopped, then you replaced a blown fuse which got you going again. Which fuse blew?

[Ingo]

With engine running in normal condition on road. At idle the voltage is somewhat lower, like 13.something.
The "charge light"  is on right after start and goes out once rpms go past 1k to 1200 or 1300 rpms and then stays out.
You might have a bad alternator that ALSO caused your battery to go down the tubes....
I find batteries to be a pain, always going bad, I finally sprung for a lithium, consistently on its special charger in the garage when parked.

[Kchop]

Hey guys,

Revisiting this problem: So, I have replaced the voltage regulator, (was told by BMW shop that the brushes on the old one were fine)
I replaced battery, (even though apparently old one was fine) Failed at one auto shop, passed at another..Finally brought it into BMW Moto shop, mechanic ran two tests from two different testers, said it was good battery. 32W alternator outputting about 13.7 at 2500rpm or so.
Bought Battery tender voltage gauge. so, am I. missing something?? Can alternator be "half-broken"? Going to drive around with voltage meter taped to gas tank (advice from shop) to see if it stops charging. Anything else that would affect battery depletion?? I've heard of something called a "parasitic draw"? anyone can comment? Also heard it doesn't usually affect k75's.
Thanks in advance.

[Kaos]

Parasitic draw is usually caused by cables connected to your battery that have functions for external hardware like phone chargers and navigation Connectors etc.
Battery depletion on a k is pretty hard when the bike is driven. Tends to only happen when your carge indicator (blue wire from the alternator isnt connected to a warning light, or faulty wiring, faulty bulb you name it.
How often do you blow a fuse, is Everything stock and what are the current issues after replacing the components and i what conditions?

[frankenduck]

The only parasitic draw should be the LCD clock in the cluster. Being an LCD clock, it takes several months to run down the battery.

[Kchop]

So, interesting. I have a aftermarket fuel pump. It has a 7.5 fuse. That blew a  few weeks ago, I replaced it and seems to have no issues. BMW tech suggested I replace that with a 10. Everything else is OEM, and as an aside before all this started happening I went a 600 mile ride( after new fuel pump was installed)  and no issues whatsoever.

[Kchop]

I should have also said that I have nothing else connected electrically. No navigation components, no external charger.

[Laitch]

So, interesting. I have a aftermarket fuel pump. It has a 7.5 fuse. . . . BMW tech suggested I replace that with a 10.

[Kaos]

Well, you're in for a ride then. Make sure your ride it around block so you wont have to haul it back home for several miles or kilometers.

But not having issue solved with battery and voltage regulator replaced and the alternator checked by BMW, there are still several other possibilities, like bad grounds that can lead to the battery to charge inefficient or badly.
or A faulty starter relay - which adds up to your bike starting when charging earlier mentioned in the post, and is in my opion worth looking at or even replacing it.
When its stuck in "on" position it will contuesly allow for power draw.
On top of that, one thing caugt my attention and that is the fuelpump. It blew your fuse and was solved by a higher amp fuse thus meaning its using more power than a standard fuelpump, in combination with either of the above or- just the charging capacity while riding on a later model k75 (which i am not too fermilliar with) could cause your bike to use more power than the bike is able to charge back into the battery.
As far as i am aware K-bikes charges the bike sufficiently to basically not having to charge your bike for several months if even not at all when driven on the regular.

[Laitch]

. . .one thing caugt my attention and that is the fuelpump. It blew your fuse and was solved by a higher amp fuse thus meaning its using more power than a standard fuelpump, in combination with either of the above or- just the charging capacity while riding on a later model k75 (which i am not too fermilliar with) could cause your bike to use more power than the bike is able to charge back into the battery.

He appears to have replaced it with a 7.5A fuse and it has worked ever since. The BMW tech recommend that he replace it with a 10A. Maybe Kchop will verify that.

The original equipment fuses with exposed filaments degrade over the years and eventually break. Replacing them with fuses with sealed filaments is good strategy.

[Kaos]

He appears to have replaced it with a 7.5A fuse and it has worked ever since. The BMW tech recommend that he replace it with a 10A. Maybe Kchop will verify that.

Yeah that is tad bit unclear to me if it's either a 7.5 or a 10amp fuse.  But if its a 10, its worth looking into.

[Laitch]

Yeah that is tad bit unclear to me if it's either a 7.5 or a 10amp fuse.  But if its a 10, its worth looking into.

When did it become okay to substitute a higher amperage fuse for a lower one? Is that a Kaos standard or what?

[frankenduck]

FYI: 4V K bikes have a 15A fuse for the fuel pump and the relay is rated for at least 20A. The Fuel relay for 2V K bikes is rated up to 40A.

[frankenduck]

FYI: 4V K bikes have a 15A fuse for the fuel pump and the relay is rated for at least 20A. The Fuel relay for 2V K bikes is rated 40A.

[Laitch]

You can say that again. 

[Kaos]

When did it become okay to substitute a higher amperage fuse for a lower one? Is that a Kaos standard or what?

Hold on, how did it become a "me" thing? 
If kchop did actually replaced the fuse with a higher amperage fuse (which he has to confirm) , the possibility is that he is depleting his battery because of the higher amperage usage of his fuel pump. So if he has its worth looking into the power usage of the fuel pump vs the charging capacity of the bike.
And not replace his fuse with a higher one if he hasnt because that will not fix the problem. Even if his fuse keeps blowing.
And also dont forget the grounds and (in my opinion worth doing in the whole matter) replace the starter relay

[Laitch]

Kaos Theory.   

[Kchop]

Kaos had me laughing because that's exactly  what happened: bike died, had to grab a kid off the street. " hey, do you have a minute..."
he thought I was trying to sell him something, hoisting that bike into van with a narrow ramp, etc.

To clarify: I have not yet replaced the 7.5  fuse with a 10. To replace was suggested by BMW Moto mechanic. The fuse blew only once after like an hour long ride. After that it seems to be fine.

According to manual, the proper fuse for that fuel pump is 7.5A.

Is there a proper way to test the starter relay? In reference to the alertnator, it either works or doesn't correct?? Has anyone experienced an alternator malfunctioning when it bike is ridden for longer rides? After bike is"hot'?

[Kchop]

Hey,
Also, unless I'm misreading..a broken or "stuck" starter relay would result in the bike trying to start even while it is already running, correct?

[Laitch]

A starter relay with welded contacts would keep the starter running while the engine is also running. The most common cause of welded starter relay contacts seems to be trying to start the Brick with a weak battery, or defective wiring to the starter relay. Many owners have installed battery quick-disconnect devices to stop the madness if it occurs. One ad hoc emergency disconnect method is to rap on the relay box with a blunt object—screwdriver handle, billy club, head butt, etc.—to jar the contacts loose from each other. Industrious owners remove the relay cover and try polishing the contacts rather than buying a new relay. This is often successful in the absence of other contributing wiring or fuse problems. Sometimes it happens once but never occurs again. Keep the battery in good condition by riding the feckin thing frequently.
 

[daveson]

So can we be confident that it was fuse six that blew?

[Laitch]

Let's vote on it!

[daveson]

I spose the odds are good for fuse six, so I'll only bet small, I'll betchya a Vegemite flavoured magnum icecream it's fuse six.